I don't think it's an American date style. More of a machine preference. Dates get filtered down in a search and other date related software functions. It is logical, when you look at one field at a time. We humans look at the whole thing at once.

__________________"The irony of the Information Age is that it has given new respectability to uninformed opinion." - John Lawton, speaking to the American Association of Broadcast Journalists in 1995